This invention relates to hemorrhoidal compositions and to a method of treating hemorrhoids and/or diseases of the anorectum using gel compositions. More particularly the invention relates to gel compositions for intrarectal administration in treating hemorrhoids and/or diseases of the anorectum and to processes for preparing said gel compositions.
Hemorrhoids are swollen varicose veins in the mucous membrane inside or just outside the rectum. They can be caused by constipation and the straining associated therewith in passing motions. The excessive pressure involved can cause a fold of the membranous rectal lining to slip down, resulting in a pinching of the veins and subsequent irritation.
Women during pregnancy are also particularly prone to suffer from hemorrhoids because of the pressure in the veins in the abdomen. Other causes include diseases of the digestive tract resulting in anal infection, and cirrhosis of the liver, where obstruction to the blood flow can occur putting increased pressure on the hemorrhoidal veins.
Once formed the hemorrhoids can further deteriorate or rupture when subjected to the additional pressure during bouts of constipation and straining or from external pressure resulting from sitting for any length of time Ruptured and bleeding piles are susceptible to infection and the swelling caused by inflammation can also exacerbate the hemorrhoids by pressing the veins.
It is possible therefore for the hemorrhoidal problems to deteriorate progressively unless effective action is taken.
Treatment methods for hemorrhoids include soothing by immersion in a warm bath, application of ointments and suppositories and surgery to control bleeding and to remove the varicose veins. A combination of such treatments may be employed in treating the disease.
A number of prior art formulations for treating hemorrhoids suggest the possibility of administering in gel form. U.S. Pat. No 4,518,583 describes a composition comprising urea, hydrogen peroxide or benzoyl peroxide, an anaesthetic and a vehicle based on a viscous solution of polyvinylpyrrolidine in glycerine. U.S. Pat. No. 4,945,084 teaches the addition of sucralfate to hemorrhoidal compositions and illustrates a gel formulation based on Samuet. No humectant or lubricant is present. EP Publication No 225832 describes a composition in gel form containing a silica gelling agent and a vegetable oil of natural origin which has been hyperoxygenated. U.S. Pat. No. 4,518,583 teaches a composition which can be in gel form for use in treating hemorrhoids and anorectal diseases comprising a peroxide and containing glycerine as humectant, emollient and lubricant.
Currently marketed topical hemorrhoidal compositions are either ointments or suppositories for application directly to the affected part or region of the body. Such compositions are generally based on a carrier comprising one or more fatty, oily or greasy components which are used to impart lubricating properties to the composition and thereby facilitate the administration of the composition by the user. The aim of such treatment is to provide the user with varying degrees of symptomatic relief in particular before and during defecation.
One of the main disadvantages of compositions based on fatty, greasy or oily components as carriers is the staining or soiling of clothing which can accompany their use. Aqueous compositions on the other hand are easier to remove from clothing. Additionally where greasy compositions are applied to affected parts by hand, users can experience added difficulties in washing their hands scrupulously clean. Yet a further disadvantage is that hydrophilic drugs are insoluble or of low solubility in fatty, oily or greasy carriers and therefore drug absorption from such compositions may be poor.
While there is a need for a hemorrhoidal carrier with satisfactory lubricant properties while possessing reduced stain or soiling properties and providing improved drug bioavailability.
It has surprisingly been found that a gel based on a water soluble cellulose derivative as gelling agent, propylene glycol as humectant and water in defined ranges possesses excellent lubricating properties and water-retaining properties such as to provide effective symptomatic relief for hemorrhoid sufferers. Such an aqueous gel base is also particularly compatible with ionic active ingredients. Further advantages of said gel base are that it avoids oily, greasy and fatty components, it is water miscible, and it is clear thereby avoiding staining or soiling of clothing. It can also be easily washed from the users hands. The combination of gelling agent and humectant also provides excellent water retaining properties after applying to the anus thereby giving a long term lubricating effect up to and during defecation. Yet a further advantage is that the large water content has a cooling and soothing effect on the user giving improved symptomatic relief.
In a first aspect, this invention provides use of an aqueous gel composition which contains one or more drugs effective in treating hemorrhoids and a carrier comprising a water soluble cellulose derivative as gelling agent in an amount from about 0.2% to about 10% by weight of the total composition, propylene glycol in an amount of from about 5% to about 45% by weight of the total composition and water in an amount up to about 94% by weight of the total composition.
This invention also provides a method of treating hemorrhoids in a human so afflicted which comprises administering intrarectally and/or to the anorectal region an aqueous gel composition which contains one or more drugs effective in such treatment and a carrier comprising a water soluble cellulose derivative as gelling agent in an amount from about 0.2% to about 10% by weight of the total composition, propylene glycol in an amount of from about 5% to about 45% by weight of the total composition and water in an amount up to about 94% by weight of the total composition.
In a further aspect, this invention provides an aqueous gel composition for intrarectal administration in the treatment of hemorrhoids and/or in the treatment of anorectal disease which contains one or more drugs effective in such treatment excluding topical corticosteroids and a carrier comprising a water soluble cellulose derivative as gelling agent in an amount from about 0.2% to about 10% by weight of the total composition, propylene glycol in an amount of from about 5% to about 45% by weight of the total composition and water in an amount up to about 94% by weight of the total composition.
To provide optimum lubricating and dispensing properties, it is preferred that the ratio of the cellulose derivative and the humectant to water are such that a gel has the viscosity from about 25000 cps to about 150000 cps @20xc2x0 C. (as measured using spindle S96 @10 rpm on a Brookfield DVII+). Preferably the viscosity is in the range 40,000 to 100,000 cps @20xc2x0 C.
In a preferred embodiment the gel formulation comprises from about 0.5 to about 5% by total weight of water soluble cellulose derivative, preferably about 1 to about 4%, most preferably about 2% by weight. Examples of cellulose derivatives useful as gelling agents are hydroxyethylcellulose, hydroxypropylmethylcellulose, methyl cellulose, methylhydroxyethylcellulose, methylhydroxypropylcellulose and carboxymethylcellulose and combinations thereof. The preferred gelling agent is hydroxyethylcellulose.
Also preferred are compositions comprising propylene glycol in an amount from about 10 to about 30% by weight, preferably about 12 to about 18% by weight, most preferably about 15% by weight.
The water present in the formulation advantageously provides a cooling effect in use and can be adjusted relative to the amounts of the other ingredients especially the gelling agent to give a satisfactory viscosity to the gel. It is preferred that the viscosity is high enough so that the gel is not too mobile and so is retained in the anus when applied thereto, yet low enough so that the gel can be dispensed satisfactorily from a tube or other dispenser. A further advantage of a water based gel is that dispensers may be cold-filled unlike grease based ointments which are generally hot filled to achieve a lower viscosity so that the tubes may be filled prior to cooling.
To achieve the desired water content, the water may be incorporated by adding some or all in the form of hamamelis water. Hamamelis water is a clear colorless liquid with astringent properties. Astringents are effective when applied to the skin or mucous membranes for a local and limited effect. Astringents coagulate the protein in the skin cells, thereby protecting the underlying tissue and decreasing the cell volume. When appropriately used, astringents lessen mucous and other secretions and help relieve local anorectal irritation and inflammation.
Hamamelis water in a concentration of 10-50% is recommended as an astringent for external use in anorectal disorders. Hamamelis water is prepared by macerating recently cut and partially dried dormant twigs of Hamamelis virginiana L in water, distilling and adding the requisite quantity of ethanol to the distillate, e.g. about 13 to 15% v/v. Typical quantities of hamamelis water used in the compositions of this invention comprise from about 10 to about 60% by weight of the total composition, e.g. 35-55%, preferably about 50% by weight. Additional water may be added to adjust the viscosity to that desired. Accordingly hamamelis water functions both as a source of one or the active ingredient for the composition (i.e. an astringent) and also for providing some or all of the water content. Ethanol is present in the hamamelis water and may therefore be another constituent of the formulations of this invention. The presence of ethanol also enhances the solubility of the active constituents and may comprise 0 to about 10% by weight of the total composition.
Other ingredients and active constituents may be incorporated in the gel composition of this invention especially other astringents, vasoconstrictors, topical steroidal anti-inflammatories, such as hydrocortisone, and/or local anaesthetics to provide symptomatic relief and/or ameliorate the pain accompanying defecation. Preferably such active ingredients are water soluble (e.g. ionic) in which case the carrier base allows a faster onset of action because the actives are held in solution. The viscous properties of the gel also minimise physical risk of loss due to run out.
Examples of astringents that may be used are zinc oxide and calamine. However hamamelis water is particularly preferred as astringent since being a solution it is particularly suited to, and mutually compatible with, the hydrophilic carrier base of this invention. It is especially preferred that the ingredients and active constituents are colourless and for this reason hamamelis water is also particularly preferred since it provides a clear formulation. Crystal clear formulations which are provided by this invention are also very much preferred because the clarity of the gel is perceived by the user as depicting cleanliness thereby optimising user confidence and user compliance.
Examples of vasoconstrictors that can be used are phenylephrine hydrochloride, ephedrine sulphate, epinephrine and epinephrine hydrochloride. The preferred vasoconstrictor is phenylephrine hydrochloride in an amount up to about 0.35% w/w of the total composition, e.g. about 0.1 to about 0.3%, preferably about 0.25%.
Phenylephrine HCl is believed to relieve itching caused by histamine release and reduces congestion in the anorectal area. It acts primarily on the alpha-adrenergic receptors and produces vasoconstriction by a direct effect on receptors rather than by norephinephrine displacement. Recommended dosage is 0.25% applied up to 4 times a day. When phenylephrine is used we have found it particularly advantageous for stability to incorporate an antioxidant system in the formulation.
Local anaesthetics that can be incorporated as active ingredients in the compositions of this invention include benzocaine (e.g. 5 to 20% by weight) benzyl alcohol (e.g. 1 to 4% by weight); dibucaine (HCl) (e.g. 0.25 to 1% by weight); lidocaine e.g. (0.5 to 5% by weight); pramoxine hydrochloride (e.g. about 1% by weight) and tetracaine (HCl) e.g. 0.5 to 1% by weight).
In a further aspect this invention provides a composition for treating hemorrhoids consisting essentially of hamamelis water up to about 50% by weight of total composition; propylene glycol from about 10 to about 20% by weight of composition; hydroxethylcellulose from about 1 to about 2.5% by weight, and water qs 100 per cent by weight. Phenylephrine hydrochloride may also be present in an amount from about 0.2 to 0.3% by weight.
The composition of the invention may also comprise further excipients including antioxidants and preservatives as required. When phenylephrine HCl is used as an active ingredient preferred antioxidants are sodium citrate (0.3 to 20%), sodium metabisulphite(0.01-1%) and disodium edetate (0.005 to 0.1%) where the figures in brackets show the preferred concentrations. Preservatives that can be used include methyl and/or propyl p-hydroxybenzoate.
In an especially preferred aspect this invention provides a topical hemorrhoidal composition as herein described in the form of an aqueous clear gel incorporating one or more soluble actives.
The compositions of this invention may be prepared by mixing the ingredients in any convenient order and allowing a gel to form. In a preferred sequence, the compositions of this invention may be prepared by dispersing the water soluble cellulose derivative in a portion e.g about ⅔ of the propylene glycol and adding to the water constituents comprising hamamelis water if required and any further active drug component and the remainder of the propylene glycol. The resulting mixture is stirred until a gel is formed, e.g for up to 1 hour.